This invention relates to medical grafting apparatus and methods for creating anastomoses and, more particularly, to apparatus and methods for creating an aortic anastomoses whose ostium diameter is larger than that of the graft conduit.
There are many medical procedures in which it is necessary to make an anastomotic connection between two tubular body fluid conduits in a patient. An anastomotic connection (or anastomosis) is a connection which allows body fluid flow between the lumens of the two conduits that are connected, preferably without allowing body fluid to leak out of the conduits at the location of the connection (see, for example, Peterson et al. U.S. patent application Ser. No. 10/147,208, filed May 14, 2002, which is hereby incorporated by reference herein in its entirety). As just one example of a procedure in which an anastomosis is needed, in order to bypass an obstruction in a patient's coronary artery, a tubular graft attached to the coronary artery downstream from the obstruction may be supplied with aortic blood via an anastomosis to the aorta. The anastomosis may be between the end of the graft and an aperture in the side wall of the aorta (a so-called end-to-side anastomosis), or the anastomosis may be between an aperture in the side wall of the graft and an aperture in the side wall of the aorta (a so-called side-to-side anastomosis).
The graft may be natural conduit, synthetic conduit, or a combination of natural and synthetic conduits. If natural conduit is used, it may be wholly or partly relocated from elsewhere in the patient (e.g., wholly relocated saphenous vein graft (“SVG”), radial artery, or partly relocated internal mammary artery (“IMA”)).
In the case of making a conventional anastomosis utilizing commercially available connectors at the proximal anastomosis between the graft and the aorta, certain difficulties may arise. First, the relative sizes of the aorta and the graft are different. Currently, the ostium diameter of the anastomosis utilizing commercially available connectors is limited by and usually smaller than the diameter of the graft. The resulting quality and amount of flow between the vein graft and the aorta, along with the provision of an effective hemodynamic seal between the two vessels, is often dependent upon the physician's skill in making an effective junction therebetween.
Second, a conventional end-to-side anastomosis utilizing commercially available connectors typically joins the graft conduit to the aorta at a substantially perpendicular angle with respect to the lumen of the aorta, thus forming a junction at the wall of the aorta. Further away from this junction, the vein graft tends to lie against the heart structure, or substantially parallel to the aorta. The transition of the vein graft from a substantially perpendicular juncture to the aorta to a substantially parallel position with respect to the aorta wall often requires non-traditional placement of the anastomosis different from that of typical hand-sewn anastomoses.
Third, it is desirable to provide an anastomosis with a diameter equal to or larger than the diameter of the smaller vessel being joined in order to allow as much area as possible for the natural healing response.
Accordingly, it is an object of the invention to provide apparatus and methods for making an anastomosis whose ostium diameter is larger than that of the graft.
It is also an object of the invention to provide apparatus and methods for making an anastomosis whose take-off is angled rather than tangential or perpendicular.